💾 Archived View for icolotl.com › repos › morgrot › old_version › morgrot.c captured on 2024-05-26 at 14:47:41.
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/* SPDX-License-Identifier: GPL-3.0-or-later */
/*
* MORGROT.C
* Morgana's Offline-First Rot13 Program (original kluge-ish C edition)
* Copyright (C) 2024 Grace Morgana <morgana@icolotl.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
int main(int argc, char* argv[]) {
// Shift amount in chars, positive = forward (e.g. A+2 -> C)
long shift;
// No Arguments, default = 13
if (argc == 1) {
shift = 13;
// One Argument, extract shift
} else if (argc == 2) {
// Detect help flags, provide usage
if (strncmp(argv[1], "-h", 2) == 0 || strncmp(argv[1], "--help", 6) == 0) {
puts("morgrot: usage:\n morgrot [base]");
return 0;
}
// Extract shift with strtol for error checking
char *end;
shift = strtol(argv[1], &end, 10);
// Check for (empty string || chars after digits || errno check)
if (end == argv[1] || *end != '\0' || errno == ERANGE) {
fprintf(stderr, "morgrot: %s: Invalid integer\n", argv[1]);
return -1;
}
// 2+ Args, error
} else {
fputs("morgrot: usage error: Too many parameters\n", stderr);
return -1;
}
// Convert to shift modulo between 0 and 25
shift = shift % 26;
if (shift < 0) {
shift += 26;
}
// Setup dynamic output array, initial size 16
int* output = malloc(4 * sizeof(unsigned char));
size_t used = 0;
size_t size = 4;
// Process chars from input until EOF
unsigned char c;
// Explicit casts as conversion may change values
const unsigned char END_OF_FILE = (unsigned char)-1;
while ((c = (unsigned char)getchar()) != END_OF_FILE) {
// Resize if necessary
if (used == size) {
size *= 2;
output = realloc(output, size * sizeof(int));
}
// Shift lowercase chars
if ('a' <= c && c <= 'z') {
c += (unsigned char)shift;
if (c > 'z') {
c -= 26;
}
// Shift uppercase chars
} else if ('A' <= c && c <= 'Z') {
c += (unsigned char)shift;
if (c > 'Z') {
c -= 26;
}
}
// Add char to dynamic array
output[used++] = c;
}
// Display array
for (size_t i = 0; i < size; i++) {
putchar(output[i]);
}
// Free dynamic array
free(output);
}